These examinations are carried out prior to starting a certain activity (aptitude test) or at regular, defined intervals (follow-up checks). The intervals between the regular follow-up checks are set forth in the Regulation relating to Health Surveillance at Work (Gesundheitsüberwachung am Arbeitsplatz, VGÜ). Aptitude tests and follow-up checks are provided for especially with regard to activities that might lead to an occupational disease (i.e. occupation-induced hearing impairment) and/or activities during which workers have to wear respiratory protection devices or are exposed to stressful heat. With the aid of these tests and checks the aptitude of workers for certain types of activities is to be determined. Should the case arise, suitable measures are to be taken to prevent the outbreak of an occupational disease. See also Voluntary Medical Examinations.